Horizontal accumulator

ABSTRACT

This invention relates to a power-driven conveyor system for transporting and accumulating a plurality of items along a path of movement from a source to a destination. The system includes a horizontally oriented section for accumulating the items along the path and an apparatus for transporting the items therealong. The apparatus may be either a plurality of parallel, spaced-apart endless belts or a plurality of conveying sections interconnected together to form an endless carrier. Each section of the carrier may constitute itself a device for directly carrying one of the items. The invention provides an effective horizontal accumulator for items on a production or an assembly line operating at a relatively high speed. The accumulator operates on the FIFO principle so that, upon a malfunction of either upstream or downstream equipment, dated or otherwise sequentially marked items are stored in such a manner that the first item into the system is the first item to come out. Additionally, the invention provides an effective horizontal accumulator for items with irregular shapes or of fragile nature. Production line backpressure does not exist so that the risk of locking or wedging of items being transported is reduced. There is also a reduced risk of breakage or quality damage. Additionally, the invention provides an effective horizontal accumulator for items requiring a particular orientation as delivered by the source. The items are maintained and delivered according to the needs at the destination.

This is a division of application Ser. No. 264,845, filed May 18, 1981,now U.S. Pat. No. 4,413,724.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a power-driven conveyor system having at leastone horizontally oriented section for accumulating items moving betweena source and a destination.

2. Description of the Prior Art

Many power-driven conveyor systems for accumulating items have sectionsoriented vertically because they take up less floor space and may bebuilt quite high. However, these systems, which usually use an endlesschain and a plurality of pulley wheels, must necessarily have the pulleywheels spaced quite a relative distance apart in order to make room forassemblies which are attached to the endless chain for carrying itemsthereon. Such exemplary prior art systems are the vertical accumulatorscovered by U.S. Pat. No. 4,168,776, issued to Hoeboer in 1979; U.S. Pat.No. 4,142,626, issued to Bradley in 1979; and U.S. Pat. No. 2,933,176,issued to Mansson in 1960.

Such vertical accumulators must be run relatively slow because theiroperation requires reliable transfer of items to be accumulated bothinto and out of the unit. This relatively slow operational speed is adefinite disadvantage.

Another disadvantage of such vertical accumulators is that theassemblies for carrying items to be accumulated are usually a freepivoting design which increases the potential for damage or breakage offragile items that are being transported or accumulated. Additionaldisadvantages of such vertical accumulators are that transfer of itemsinto such units usually requires mechanical movement of the items to beaccumulated which increases the breakage potential of fragile items. Inaddition, this mechanical movement of items is generally recognized asbeing a potential cause of lower production efficiencies because ofproblems historically associated with these mechanical movements. Also,the assemblies for carrying items to be accumulated do not usuallyaccommodate irregular shapes and sizes because of their inability toreliably transfer and contain such items.

Because of the presence of such carrier assemblies, it has also been aproblem to condense the arrangement of the endless chain and theplurality of pulley wheels into a volume occupying significantly lessfloor space.

There are horizontal accumulators known in the prior art. Exemplarysystems are shown in U.S. Pat. No. 3,506,105, issued to Stauber in 1970,U.S. Pat. No. 3,448,846, issued to Bardenhagen in 1969, U.S. Pat. No.3,370,693, issued to Marsden in 1968; and U.S. Pat. No. 2,932,376,issued to Millington in 1960. However, many prior art horizontalaccumulators operate on the LIFO principle, i.e., upon a malfunction ofeither upstream or downstream equipment, the items are stored in theaccumulator in such a manner that the last item into the system is thefirst item out of the system when the malfunction in the equipment iscorrected and the upstream or downstream equipment is up and runningagain. This LIFO principle of operation is a disadvantage in systemswhere maintaining sequence of manufacture is important. This LIFOprinciple of operation also affects reliability in that accumulateditems must be reintroduced into the same stream of items being deliveredby the source. This reintroduction negatively affects item quality andproduction line efficiencies.

Horizontal accumulators do exist that operate on the FIFO principle,i.e., first in first out. However, these systems carry with them thedisadvantages of breakage or damage caused by production line backpressure or less than acceptable production efficiencies in thatproduction line back pressure results in locking or wedging of theaccumulated items which in turn results in lower production lineefficiencies. In addition, many horizontal accumulators that operate onthe FIFO principle demand that the accumulated item be mechanicallypushed from one portion of the conveying means to another portion of theconveying means. This mechanical pushing results in lower productionline efficiencies when changing direction of movement from one directionto another, in that the probability of jamming or falling is increased.Many horizontal accumulators, both FIFO and LIFO, have great difficultyin maintaining the items in the same orientation as delivered by thesource, e.g., labels on one side, pour spout at top, handle leading,etc. This fact negatively affects production line efficiencies.

SUMMARY OF THE INVENTION

The present invention relates to a power driven conveyor system havingat least one horizontal section for accumulating items moving between asource and a destination.

It is a primary object of the present invention to provide an effectiveand reliable accumulator for items on a production or an assembly lineoperating at a relatively high speed.

It is another primary object of this invention to operate an accumulatoron the FIFO principle, i.e., upon a malfunction of either upstream ordownstream equipment, dated or otherwise sequentially manufactured itemsare stored so that the first item into the system is the first item tocome out. Such dated items are most important in industries handling andpackaging fresh foods, e.g., meat, cheese, poultry and candy. Datedproducts are also important in the canning, frozen foods and health careindustries. Items marked in a particular sequence are likewise importantin the paper, toiletry, automotive and electronic industries.

It is another object of the present invention to ensure the orientationof items to be accumulated is not changed, as delivered from the sourceand required by the destination.

It is another object of the present invention to provide the capabilityfor reliable transfer from one direction of movement to anotherdirection of movement of items to be accumulated, thereby enabling highoperational speed with no sacrifice in production line efficiency.

It is another object of the present invention to decrease the potentialfor damage or breakage as well as jamming or wedging of items to beaccumulated because of multiple direction transfer points or productionline back pressure.

It is another object of the present invention to provide effective andreliable containmnet of irregular shaped and sized items to beaccumulated.

The accomplishment of these and other objects to be discussedhereinafter will become readily apparent from the following descriptionof various embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view showing an arrangement of an endless conveyingmeans and a plurality of turning wheels in one embodiment of ahorizontal accumulator;

FIG. 2 is a partial top plan view of a plurality of interconnectedpulley wheels;

FIG. 3 is a close-up top plan view of a drive mechanism shown in FIG. 1;

FIG. 4 is a close-up side elevational view of the drive mechanism shownalong line 4--4 in FIG. 1;

FIG. 5 is a close-up top plan view of a discharge or helper drive shownin FIG. 1;

FIG. 6 is a close-up side elevational view of the discharge or helperdrive shown along line 6--6 in FIG. 1;

FIG. 7 is an exploded view showing the details of a slide assembly usedfor moving a pair of interconnected pulley wheels along the accumulatorshown in FIG. 1;

FIG. 8 is a top plan view showing an arrangement of endless conveyorbelts and a plurality of slide assemblies in a second embodiment of ahorizontal accumulator;

FIGS. 9A and 9B are side elevational and top plan views of a chain forcarrying a deck of slats with a plurality of item guide rails forsupporting a plurality of items to be accumulated during theaccumulation cycle, on the horizontal accumulator shown in FIG. 1;

FIG. 10 is a close-up view of the chain and item guide rails shown alongline 10--10 in FIG. 9A;

FIG. 11 is a close-up side elevational view taken along line 11--11 ofthe chain and item guide rails shown in FIG. 10;

FIG. 12 is a perspective view showing tongue and groove connectionsforming a plurality of chain links making up an endless conveying meansfor carrying items to be accumulated thereon;

FIG. 13 is a perspective view showing item carriers attached to aplurality of chain link plates, or similar conveying means, making up anendless chain for carrying a plurality of stacked thin items, such aswrapped cheese slices, thereon; changes in item carrier designs willaccommodate a wide range of differently sized and shaped items to beaccumulated thereon;

FIGS. 14-16 are partial top plan views showing various movements of theendless conveying means around one end of a small sized modification ofthe embodiment shown in FIG. 1;

FIGS. 17-20 are top plan views showing various operating stages of theendless conveying means of a moderately sized version of the embodimentshown in FIG. 1;

FIG. 21 is a partial top plan view of one end of a modification of theembodiment shown in FIG. 1;

FIG. 22 is a perspective view showing a multi-tiered arrangement of themoderately sized version of the embodiment shown in FIGS. 17-20; thisarrangement provides additional accumulation capacity with no increasedfloor space requirement; and

FIG. 23 is a perspective view showing a suspended arrangement of themoderately sized version of the embodiment shown in FIGS. 17-20; thisversion will accommodate items to be accumulated that are suspendedrather than transported as shown in the aforementioned drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a power driven conveyor system 10 for transporting andaccumulating a plurality of items 2, shown but not confined to items inFIGS. 12 and 13, along a path of movement, indicated by arrow heads,from an infeeding source IN to an outgoing destination OUT. The system10 has a horizontally oriented accumulator section 20 for accumulatingthe plurality of items 2 along the path of movement.

An endless conveying means 40 transports the plurality of items 2 alongthe path. A plurality of chain links 3, shown in FIGS. 12 and 13, areinterconnected to form this version of endless conveying means 40 whichis driven by an infeed drive mechanism 61, shown in detail in FIGS. 3and 4.

For the sake of clarity hereinafter, it should be pointed out that thedesignation H refers to pulley wheels on the horizontal section 20;designation A refers to the infeeding or accumulating side of system 10;and designation D refers to the exit or discharging side of system 10.

A plurality of fixed pulley wheels 70H are arranged at one end of thesection 20. A plurality of interconnected pairs of pulley wheels 70W and70X are shown adjacent to the plurality of fixed pulley wheels 70H. Thefixed pulley wheels 70H and the pulley wheels 70W guide the endlessconveying means 40 along the serpentine path of movement indicated bythe darkened arrow heads. The pulley wheels 70W and 70X areinterconnected in pairs by slide assemblies 80, shown in detail in FIG.7. The assemblies 80 stretch out or otherwise extend the length of thepath of movement of items 2 around pulley wheels 70H and 70W,alternately, in a manner to be described in detail hereinafter in regardto FIGS. 14-23.

Another plurality of fixed pulley wheels 71H is arranged at the otherend of section 20. The assemblies 80 may slide from the positionadjacent to the fixed pulley wheels 70H to a maximum distance at aposition adjacent to the fixed pulley wheels 71H when accumulating items2 on the endless conveying means 40. The extreme position of one slideassembly 80 adjacent to the wheels 71H is shown in phantom lines in FIG.1.

As shown in FIG. 2, a plurality of slide assemblies 80 may beinterconnected by one or more cross braces 88 so that all assemblies 80slide together away from the position adjacent to pulley wheels 70H.

An infeed drive mechanism 61, shown in detail in FIGS. 3 and 4, controlsthe accumulation of incoming items 2 on endless conveying means 40. Thedischarge drive mechanism 62, shown in detail in FIGS. 5 and 6, controlsthe discharge of outgoing items 2 from endless conveying means 40. Thesetwo drive mechanisms 61 and 62 work in conjunction with each other.Their key components are driving motors 61A and 62A, respectively.

Now viewing FIGS. 3 and 4 in particular with FIG. 1, it may be seen thatendless conveying means 40 enters the area of the infeed drive mechanism61 by moving horizontally, as shown in the top plan view of FIG. 3.Conveying means 40 goes around a first fixed pulley wheel 71HA so thatits direction of travel is reversed and it moves to the left. Conveyingmeans 40 then goes down around and under a second fixed pulley wheel61D, best shown in FIG. 4. Wheel 61D is driven directly by belt 61Bwhich is, in turn, driven by small pulley wheel 61C attached directly tothe motor 61A. Conveying means 40 then moves up a slight incline to theright and is deflected sideways by a guiding means including an idlingwheel 91W over tensioning roll 91T. Conveying means 40 moves down aslight decline, then under and around a third pulley wheel 61E. Thedirection of travel of conveying means 40 is once again reversed as itmoves over the top of pulley wheel 61E to the left. The conveying means40 moves sideways around post 91, which is shown in FIGS. 1, 3 and 4,and then it is deflected into a straight horizontal path as it movesaround post 101, shown only in FIG. 1. Conveying means 40 now movestoward the infeeding source IN where items 2 are fed thereon near, butlimited to, the first fixed pulley wheel 70HA, as best shown in FIG. 1.

In FIG. 1, there is one main discharge drive mechanism 62 on the exitside of section 20 and a plurality of helper drive mechanisms 63 whichare substantially identical to the main discharge drive mechanism 62.The number of helper drive mechanisms 63 will depend upon the length ofthe endless conveying means 40 and the combined weight of the pluralityof items 2 carried thereon. In the embodiment shown in FIG. 1, there aretwo such helper drive mechanisms 63.

Now viewing FIGS. 5 and 6, in particular, with FIG. 1, it may be seenthat endless conveying means 40 leaves the outgoing destination OUT andenters the area of the discharge drive mechanism 62 by movinghorizontally, as best shown in the top plan view of FIG. 5. After goingaround the fixed pulley wheel 70H, conveying means 40 goes down andaround under a second fixed pulley wheel 62D so that its direction oftravel is reversed as it moves laterally to the left. Wheel 62D isdriven directly by belt 62B which is, in turn, driven by small pulleywheel 62C attached directly to the motor 62A. Conveying means 40 movesover tensioning roll 92T, then around a third pulley wheel 62E so thatthe direction of travel of conveying means 40 is again reversed to theright. Post 92 deflects conveying means 40 sideways so that it goesaround fixed pulley wheel 71HD, once more reversing the direction oftravel of conveying means 40, which now travels toward pulley wheel 70Xon slide assembly 80 at the opposite end of section 20, best shown inFIG. 1.

The periodic reversing of direction and looping of the conveying means40 around the various pulley wheels is necessary in order to preventslack in the conveying means 40, particularly if it is very long, and toensure that the required drive power is transmitted effectively.

FIG. 7 shows an exploded view of the details of the slide assembly 80which interconnects a pair of pulley wheels, such as wheels 70W and 70Xshown, for example, in FIG. 1 on section 20. For example, wheels 70W and70X are interconnected by bolts 81, shown in FIG. 7, through theircenters at opposite ends of a bar 82 and a frame. For schematicpurposes, only bar 82 is shown as a representation of slide assembly 80in the embodiments of FIGS. 1, 2 and 14-23. Section 20 has suspendedtracks (not shown) running parallel to and underneath the endless chain40. Slide assembly 80 has roller wheels 84 which roll on the tracks andguide blocks 85 which slide along underneath the tracks. The endlessconveying means 40 travels in grooves 86 as it moves around the wheels70W and 70X. The plurality of items 2 are prevented from falling off themoving endless conveying means 40 as it moves around wheels 70W and 70Xby guide rails 87 attached to the frame by posts 89.

A second embodiment of the horizontal accumulator of the presentinvention is illustrated in FIG. 8. Instead of the single horizontallyoriented section 20, the endless conveying means 40, the plurality offixed pulley wheels 70H-71H, and the plurality of interconnected pairsof pulley wheels 70W-70X on the slide assembly 80 shown in FIG. 1, thissecond embodiment has a plurality of horizontally oriented parallelconveyor belts 121-124 driven in opposite directions, no endless chain,no fixed pulley wheels, and a plurality of single pulley wheels 170mounted on a plurality of slide assemblies 180. Guide rails 187 divertthe direction of travel of items to be accumulated, from traveling tothe left on conveyor 121 onto slide assembly 180 which, by rotatingpulley wheel 170 and by the force of the items 2 therebehind, redirecteach item 2 onto conveyor 122 traveling to the right. Posts 189 secureeach guide rail 187 to each slide assembly 180. Each guide rail 187 hasfree ends 188 which extend across and above but do not contact eachconveyor 121-124. The free ends 188 are curvilinear and act as catchersfor diverting the flow of the items 2 from one conveyor belt travelingin one direction to the next parallel belt traveling in the oppositedirection.

FIGS. 9-11 show a modified version of the first embodiment of thehorizontal accumulator shown in FIG. 1. This modified version isparticularly adapted for accumulating tall items, such as but notlimited to, bottles 2, shown in FIG. 10, and may also be used with thethree embodiments shown in FIGS. 14-22 to be described hereinafter.

In FIG. 9A, the slide assembly 80 is shown in an intermediate positionbetween fixed pulley wheel 70H at one end of horizontal section 20 andfixed pulley wheel 71H at the other end of section 20. In FIGS. 9B and10, a plurality of upstanding guide posts 288 are fixed along the outerside of the path of movement for the plurality of items 2. In FIGS. 9B,10 and 11, there is shown a plurality of substantially identicalupstanding guide posts 289 which travel with the plurality of items 2along the inner side of the path of movement of items 2.

As best shown in FIGS. 10 and 11, each of the plurality of outer andinner guide posts 288 and 289 carry guide rails 287 for preventing thetall items 2 from falling off the chain links 3 upon which each of theitems 2 travel. Each pair of the plurality of inner guide posts 289 issecured to one of a plurality of slats 290 which are interconnected toeach other in order to form a deck and are carried by an endless chain240, best shown in FIG. 11, which goes around two large sprocket wheels260. By viewing FIG. 9A, it may be seen that the two sprocket wheels 260are positioned near to the opposite ends of the horizontal section 20.There are a plurality of spaced-apart, parallel endless chains 240, eachof which carries one side of a separate deck of slats 290, independentlyof but interlockingly connected with the endless chain 240 to each slideassembly 80.

As may be seen from FIGS. 9A and 9B, when slide assembly 80 moves allthe way next to fixed pulley wheel 71H at one end of horizontal section20, the right half of the deck of slats 290 with guide posts 289 ispulled all the way up and around onto the top side of section 20 so thatguide posts 289 fill substantially completely the space between endlessconveying means 40 from one end near pulley wheel 70H to the other endnear pulley wheel 71H on section 20. At the same time, the left half ofthe deck of slats 290, shown without the guide posts 289 in FIG. 9B, isretracted onto the underside of section 20. However, as slide assembly80 moves away from fixed pulley wheel 71H toward the pulley wheel 70H atthe other end of section 20 in order to accumulate items 2 on theextended conveying means 40, the movement of endless chain 240 issynchronized by conventional electrical switching means with themovement of endless conveying means 40 so that the retracted guide posts289 are pulled up around sprocket wheels 260 from underneath thehorizontal section 20. When slide assembly 80 has reached the other endof section 20 near fixed pulley wheel 70H, all retracted guide posts 289are on the top side of section 20 while the half of the deck of slats290 without guide posts 289 are stored on the underside of section 20.

FIGS. 12 and 13 show two typical, but not limited to, embodiments of aplurality of interconnected conveying sections 3 for carrying items 2 tobe accumulated. The illustrated embodiments of the interconnectedconveying sections 3 are versions of basic pivot radius tab table topconveyors (manufactured by the Budd Company) and roller chains(available from a multitude of manufacturers).

FIG. 12 shows one of a plurality of items 2, in this case, an irregularshaped container, being transported along part of the path of movementof the table top conveyor which is made up of the plurality ofinterconnected conveying sections 3. In this first embodiment of thetable top conveyor, each conveying section 3 constitutes itself apotential device for directly carrying one or more of the plurality ofitems 2. Thus, there is no need, as in the prior art, to have a separateassembly for carrying an item 2 alongside each conveying section 3. Eachof the plurality of conveying sections 3 has a groove 8 and a bolt 9 forswinging movement through an arc 11 about a tongue 12 of aninterconnected conveying section 3.

FIG. 13 shows one of a plurality of items 2, in this case, but notlimited to, a wrapped stack of thin cheese slices, being transportedalong part of the path of movement of the plurality of conveyingsections 3, in this case, a roller chain which forms the endlessconveying means. In this second embodiment, the device for directlycarrying one of the plurality of items 2 is a plate 14 for retaining thewrapped stack thereon. Each plate 14 has upturned ends 15 which helpretain the wrapped stack 2 thereon. Thus, ends 15 counteract thecentrifugal force which acts tangentially to the path of movement andwhich tends to throw the stack 2 off plate 14 whenever the endlessconveying means goes around a pulley wheel. Each plate 14 also hastapered sides 16 which allow the limited swinging movement required wheneach plate 14 is going around a pulley wheel.

The operation of the power-driven conveyor system 10 on section 20 willnow be described by reference to FIGS. 14-23 which show the endlessconveying means 40 generally and not each of the plurality of individualconveying sections 3 that carry items 2. Also, the embodiments shown inFIGS. 14-23 differ from the systems shown in FIGS. 1 and 8 in that theinfeed drive mechanism 61 and the discharge drive mechanism 62 directlycontrol fixed pulley wheels 71HA and 71HD, respectively, as shown inphantom lines in FIGS. 4 and 6, by way of belts 61B and 62B, pulleywheels 61C and 62C, driving bevel gears 61F and 62F, and driven bevelgears 61G and 62G. In the embodiment shown in FIG. 1, these wheels 71HAand 71HD are controlled through intermediate drive pulley wheels 61D and62D, respectively shown in FIGS. 4 and 6, around which endless conveyingmeans 40 is looped underneath section 20. Thus, in the embodiments ofFIGS. 14-23, the endless conveying means 40 remains at all timessubstantially parallel to the horizontal section 20. One advantage ofthis arrangement is that the slide assembly 80 may extend the conveyingmeans 40 substantially completely between the fixed pulley wheels 70H atone end of section 20 and the fixed pulley wheels 71H at the other endof section 20, thereby increasing the amount of space available foraccumulating items 2 on conveying means 40 as the latter travels alongits path of movement on section 20.

FIGS. 14-16 show an embodiment of the conveyor system 10 for a smallhorizontal accumulator with a short amount of storage space and time.

In FIG. 14, conveying means 40 follows a path of movement around leftpulley wheel 70H, wheel 70W, and then right pulley wheel 70H. Wheels 70Wand 70X are fixed to the slide assembly 80 which is stationary duringnormal operations when infeed of items 2 equals the discharge thereof.

In FIG. 15, conveying means 40 follows the path of movement around thesame wheels, 70H, 70W and 70H, but the path is lengthened because thereis only infeed of items 2 and no discharge. Thus, accumulation of items2 on conveying means 40 is occurring because slide assembly 80 is movingpulley wheels 70W and 70X away from fixed pulley wheels 70H.

In FIG. 16, the path of movement is shortened because there is no infeedand only discharge of items 2, or because the discharge of items 2 isfaster than the infeed of items 2. Discharge occurs because slideassembly 80 is moving pulley wheels 70W and 70X toward fixed pulleywheels 70H.

FIGS. 17-20 show an embodiment of the conveyor system 10 for amoderately sized horizontal accumulator having a fair amount of storagespace and time. Infeed begins between pulley wheels 71HA and 70H at aposition located adjacent to wheel 71HA. Discharge occurs between pulleywheels 71HD and 70H at a position located directly adjacent to wheel71HD. These wheels 71HA and 71HD are driven independently by infeeddrive mechanism 61 and discharge drive mechanism 62, respectively, in amanner somewhat similar to the arrangement shown in FIGS. 3-6.

Basically, during normal operations when infeed equals discharge, bothwheels 71HA and 71HD are being driven. During accumulating operationswhen there is only infeed, wheel 71HA alone is driven. Duringdischarging operations, wheel 71HD is driven alone or at a somewhatfaster speed than wheel 71HA is being driven. The infeed onto and thedischarge of items 2 from conveying means 40 may be done either manuallyor automatically by known means.

As shown in FIG. 17, when downstream equipment X, such as, but notlimited to a casepacker, malfunctions or is otherwise DOWN, the system10 allows infeed to continue. Items 2 are accumulated on conveying means40 which has its path of movement lengthened by having slide assemblies80 sequentially move away from fixed wheels 70H toward fixed wheels 71H.This accumulation is accomplished by shutting off motor 62A, shown inFIGS. 5 and 6, so that pulley wheel 71HD no longer drives conveyingmeans 40.

Because motor 61A shown in FIGS. 3 and 4 is still running, slack inconveying means 40 results so that pulley wheel 71HA pulls thereon, asindicated by double arrows therearound, in order to lengthen the path ofmovement by sequentially shifting slide assemblies 80 away from fixedpulley wheels 70H. This accumulation of items 2 in system 10 eliminatessource downtime or the need to manually or automatically remove theitems 2 from the conveying means 40.

As shown in FIG. 18, as soon as downstream equipment, as indicated withX in FIG. 17, is up and running again, the system 10 returns to itsfunction as a conveyor and discharges the items 2 in the same order inwhich they were received from the infeeding source IN. Motor 62A, shownin FIGS. 5 and 6, is turned on again. Pulley wheel 71HD may be runfaster by the motor 62A than pulley wheel 71HA is run by the motor 61A.As indicated in FIG. 18 by triple arrows around pulley wheel 71HD, thereis a pull generated on conveying means 40 in order to shorten the pathof movement thereof. This pull results from motor 62A operating fasterthan motor 61A.

As shown in FIG. 19, eventually the system 10 may be returned to asituation in which the conveying means 40 has its shortest possible pathof movement around pulley wheels 70H and 70W, alternately.

On the other hand, motor 62A, shown in FIGS. 5 and 6, may be left idlingafter the downstream equipment X is up and running again in order tocompletely fill the system 10 with items 2. In such a situation, whichis not illustrated in the drawings, the pulley wheel 71HA is driven bymotor 61A so that all slide assemblies 80 are sequentially moved awayfrom fixed pulley wheels 70H at one end of section 20 and are shiftedadjacent to fixed wheels 71H at the other end of section 20.

Likewise, motor 62A may be run at the same speed as motor 61A as soon asdownstream equipment X is up and running again so that the path ofmovement of items 2 on conveying means 40 remains as shown in FIG. 18.Thus, there is at least some accumulation of items 2 in the system 10 inthe event that the upstream equipment X malfunctions or is otherwiseinoperative.

As shown in FIG. 20, infeed is halted by a breakdown in the upstreamequipment X but there is at least partial accumulation of items 2 in thesystem 10. In this situation, motor 61A, shown in FIGS. 3 and 4, isturned off and motor 62A is left switched on. Pulley wheel 71HA stopsdriving conveying means 40 and is left idling, as indicated by the onearrow therearound in FIG. 20. Motor 62A continues to drive pulley wheel71HD, as indicated by the double arrows therearound in FIG. 20, so thatitems 2 continue to be discharged from conveying means 40 to downstreamequipment, such as but not limited to the case packer (not shown). Theidling of pulley wheel 71HA creates a slack in conveying means 40 sothat wheel 71HD pulls thereon in order to shorten the path of movementby causing slide assemblies 80 to sequentially shift away from fixedpulley wheels 71H and toward fixed pulley wheels 70H. This discharge ofitems 2 from the system 10 will continue until the conveying means 40achieves once again the shortest possible path of movement, shown inFIG. 19, around wheels 70H and 70W, alternately. Thus, the downstreamequipment may continue to operate, without lost production time, untilthe upstream equipment X is up and running again or until the system 10is emptied of all items 2 accumulated therein.

Of course, the larger the area occupied by section 20 or the greater thenumber of planar sections 30, to be discussed hereinafter, added in avertical tier with section 20, the longer will be the possible path ofmovement with its resultant increased capacity of accumulation of items2 in the system 10.

FIG. 21 shows another embodiment of section 20 with the arrangement offixed pulley wheels 70H and pairs of pulley wheels 70W-70Xinterconnected by slide assemblies 80. The plurality of pulley wheels70W, 70X and 70H are aligned for greater density by the imposition byposts 90. These posts 90 are stationary and effectively change the pathof movement of the endless conveying means 40 around the pulley wheels70H, 70W and 70H so that the path is condensed into an area smaller thanthe area that would be occupied by the same number of pulley wheels inthe embodiment of section 20 as it is shown in FIG. 1.

FIG. 22 shows another embodiment of the power-driven conveyor system 10for transporting and accumulating the plurality of items 2, shown inFIGS. 12 and 13, along the path of movement, indicated by arrow heads,from an infeeding source IN to an outgoing destination OUT. The system10 has the horizontally oriented accumulator section 20 for accumulatingthe plurality of items 2 along the path. An additional horizontalaccumulator section 30 is arranged above the lower section 20 toincrease the overall accumulating capacity of the system without anyincrease in the required floor space. Additional tiers may be added, ifdesired.

In the embodiment shown in FIG. 22, the endless conveying means 40transports the plurality of items 2 along the path of movement in thesame manner as shown in FIGS. 14-21. The plurality of conveying sections3, shown in FIGS. 12 and 13, are interconnected to form the endlessconveying means 40. A second endless conveying means 50 assists endlessconveying means 40 in its movement from an exit point 4 of thehorizontally oriented section 20 at the bottom of the vertical tier toan inlet point 5 of the additional planar section 30. Endless conveyingmeans 50 renders this assistance to endless conveying means 40 byconnecting thereunder so that both conveying means 40 and 50 travel intandem up the spiraling path of movement from point 4 to point 5.Conveying means 50 is driven by a motor 60 while conveying means 40 isdriven by infeed drive mechanism 61, shown in detail in FIGS. 3 and 4,and by discharge drive mechanism 62, shown in detail in FIGS. 5 and 6.

Hereinafter, the designation P is used to refer to pulley wheels on theplanar section 30. The plurality of fixed pulley wheels 70H is arrangedat one end of the horizontally oriented section 20 while a similarplurality of fixed pulley wheels 70P is arranged on the same end of theadditional planar section 30. These fixed pulley wheels 70H and 70Pguide the endless conveying means 40 along the path of movementindicated by the arrow heads. The plurality of interconnected pairs ofpulley wheels 70W and 70X is also arranged on the horizontally orientedsection 20 while a similar plurality of pulley wheels 70Y and 70Z isarranged on the additional planar section 30. The pulley wheels 70W-70Xand 70Y-70Z are interconnected in pairs by the slide assemblies 80,shown in detail in FIG. 7. The assemblies 80 stretch out or otherwiseextend the length of the path of movement of items 2 along sections 20and 30 in the manner described in detail hereinbefore in regard to FIGS.14-21. A plurality of driving pulley wheels 71H is arranged at the otherend of the horizontally oriented section 20 while a similar plurality ofdriving pulley wheels 71P is arranged at the same end of the additionalplanar section 30. The key driving pulley wheels are wheels 71HA and71PA which control the accumulation of the items 2 on their respectivesections 20 and 30. Wheels 71HA and 71PA are interconnected by driveshaft 6 for simultaneous rotation and are controlled by infeed drivemechanism 61. Other key driving pulley wheels are wheels 71HD and 71PDwhich control the discharge of the items 2 from respective sections 20and 30. Wheels 71HD and 71PD are interconnected by drive shaft 7 forsimultaneous rotation.

FIG. 23 shows the horizontally oriented section 20 arranged with aplurality of hooks 17, each capable of holding an item to beaccumulated. The section 20 may be suspended from an overhead support,such as ceiling (not shown) of a building, by legs 100. Necessarily, theinfeed and discharge drive mechanisms 61 and 62 are arranged above thedriving pulley wheels 71H. Otherwise, the embodiment of section 20 shownin FIG. 23 has the same elements and operates in the same manner as theembodiment of section 20 shown in FIG. 22.

In conclusion, it must be pointed out that the foregoing preferredembodiments are considered as illustrative only. Numerous othermodifications and changes will readily occur to those skilled in the artof power-driven conveyors and, consequently, the disclosed invention isnot limited to the exact constructions and operations shown anddescribed hereinabove.

I claim:
 1. A power drive conveyor system for transporting a plurality of articles, comprising:a horizontally oriented section for accumulating the plurality of articles; an endless conveying means for transporting the plurality of articles along a horizontal serpentine path of movement on the horizontally oriented section from a source to a destination; said conveying means having a substantially continuous article supporting surface for permitting said articles to be infed onto and discharged from said conveying means on a continuous basis while said conveying means is in motion; horizontally operated slide assembly means for reversibly extending the length of the serpentine path of movement of the endless conveying means on the horizontally oriented section; a first plurality of fixed pulley wheel means, arranged on one end of the horizontally oriented section, for moving the endless conveying means around alternate fixed pulley wheel means and said slide assembly means along the serpentine path of movement on said horizontally oriented section; and drive means for sequentially moving said slide assembly means and said endless conveying means associated therewith away from or towards said fixed pulley wheels to change the length of said accumulating section; said drive means including an infeed drive mechanism and a discharge drive mechanism working in conjunction therewith, at least one of said infeed drive mechanism and said discharge drive mechanism comprising: a first pulley wheel which directs said conveying means in a first direction along said horizontally oriented section; a second pulley wheel which directs said conveying means below said horizontal plane in a direction approximately opposite to said first direction; a third pulley wheel which directs said conveying means back to said first direction along said horizontally oriented section; whereby the occurrence of slack is prevented in said conveying means and the required drive power is transmitted effectively and whereby the transported articles are accumulated on and discharged from the horizontally oriented section on a first-in, first-out basis, accumulated without any significant item back-pressure, and without any loss in orientation as delivered by the source and as required by the destination.
 2. The system, according to claim 1, further comprising a plurality of interconnected together conveying section means for forming the endless conveying means, wherein each of the plurality of conveying section means constitutes itself a means for directly carrying the plurality of items.
 3. The system according to claim 1, wherein said conveyor article supporting surface comprises interconnecting plate means for transporting the plurality of articles thereon.
 4. The system, according to claim 3, wherein said plate means has tapered side means for allowing limited swinging movement of a tongue in a groove of an interconnected one of the plurality of conveying section means.
 5. The system, according to claim 1, wherein the slide assembly means includes a plurality of interconnected pairs of pulley wheels.
 6. The system, according to claim 1, further comprising a plurality of post means, arranged on the horizontally oriented section, for changing the path of movement on the horizontally oriented section.
 7. The system, according to claim 1, further comprising a second plurality of fixed pulley wheel means, arranged on the other end of the horizontally oriented section, for moving the endless conveying means on said horizontally oriented section, and drive means for rotating the second plurality of fixed pulley wheel means.
 8. The system, according to claim 5, further comprising frame means for interconnecting the plurality of interconnected pairs of pulley wheels.
 9. The system, according to claim 1, further comprising cross brace means for interconnecting each of the slide assembly means whereby a plurality of said slide assembly means move simultaneously to extend the length of the path of movement of the endless conveying means on the horizontally oriented section.
 10. The system, according to claim 1, further comprising upstanding guide means for laterally supporting said articles being transported along the path of movement.
 11. The system, according to claim 10, wherein the guide means include retractable means in cooperative association with said conveying means.
 12. The system, according to claim 1, wherein said infeed drive mechanism and said discharge drive mechanism further comprise a means for guiding said conveying means between said second pulley wheel and said third pulley wheel.
 13. The system, according to claim 1, wherein both of said infeed drive mechanism and discharge drive mechanism comprise the first, second, and third pulley wheel arrangement.
 14. The system, according to claim 12, wherein said conveying means is deflected laterally by said guiding means between said frst and second pulley wheels.
 15. A horizontal power drive conveyor system comprising:a conveying means for transporting and accumulating a plurality of upstanding articles from an infeed to a discharge along a substantially horizontal path of movement, said conveying means including at least two conveying sections traveling in opposite directions, said sections each having an article accumulating portion and a non article-carrying portion, both of said portions being reversibly extendable; upstanding guide means for providing lateral support for said articles, said guide means being reversibly extendable in cooperation with said article accumulating portion of said conveying section so that the length of said guide means along said article accumulating portion varies in direct relation as the length of said article accumulating portion of said section varies.
 16. The horizontal power drive conveyor system of claim 15, wherein said upstanding guide means further comprises a series of inner guide posts disposed between said at least two conveying sections and outer guide posts disposed at the side of said conveying sections opposite said inner guide posts.
 17. The horizontal power drive conveyor system of claim 15, further including slat means for forming a movable deck, said slat means being operatively connected to said upstanding guide means. 